As is well known, there are many model railroad enthusiasts around the world, many of whom build their own model railroads. In most of these model railroads, the motive device on the model train operates on direct current in a specific manner. For example, a typical rail system may comprise a track section comprising right and left hand rails of opposite polarity. If the potential difference between the rails is of a first polarity, the train will proceed in a first direction. This applies no matter what direction the engine having the motive device is facing.
A problem arises when the hobbyist lays track in a loop having an outlet, such a configuration being extremely common in such track layouts. Normally, a direct connection of the tracks of the loop would constitute a direct short circuit across the tracks making the train inoperable. Typical prior art solutions to this problem is to insulate the loop track from the straight outlet track, thus making each section a separate block whose electrical polarity is separately switchable. For example, the train can proceed from a first or straight block to a second block or loop block on a straightaway portion. With the typical insulating arrangement described above, there is no short circuit. But when the train reaches the point where a change of polarity has been made on a loop section, the polarity is such that the motive device will be caused to reverse when crossing that particular point. Unless compensated for, the train will run back and forth across the point. In order to compensate for this, the operator usually switches the polarity of the initial straightaway block while the train is traveling on the loop so that when the train again crosses the loop insulating point, the polarity is correct for the train to continue in the opposite direction along the straightaway loop.
The aforementioned need for polarity switching unnecessarily complicates model train operation and detracts from the realism for which most railroad hobbyists strive. In addition, it is difficult for younger enthusiasts to master the switching controls of such a system, which can become very complex when the track layout includes several loops and blocks.